Continuous circumference diffuser reaction canister

ABSTRACT

Featured for use in the reaction canister of an inflatable restraint system is a continuous circumference diffuser tube. The diffuser tube may be a one-piece, two-piece or clamshell type all of which functionally are the same although the clamshell type is more versatile. The diffuser tube provides for the attachment of brackets for installation of the reaction canister in the instrument panel of a vehicle, provides a secure reliable attachment for the inflatable bag or protective cushion, and a secure installation of the inflator. The diffuser tube completely encloses the inflator and allows a last operation of assembly thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a passenger passive restraint air bag module,and more particularly, to an improvement therein designed to minimizedeformation thereof and also possible damage to the dashboard orinstrument panel of an automotive vehicle during deployment of the bag.The improvement is in the structure internal to the module for housingand positioning the gas generator or inflator and the air bag and fordirecting the inflating gas flow or jet for best deployment of the bag.

2. Description of the Prior Art

Some terminology herein is used for convenience in reference only and isnot intended to be limiting. The words "forwardly" and "rearwardly"refer to the normal forward and reverse directions of travel of thevehicle to which a passenger passive restraint module is attached. Theword "thrust neutral" refers to the production by an inflator of zerothrust when accidentally initiated as, for example, during shipping,storage or handling. That is to say, the gas discharge openings in theinflator are so positioned that the gas is discharged in opposingdirections whereby there are no resulting forces tending to causephysical movement of the inflator. Hence, the inflator will expend theenergy generated thereby, generally in place.

The state of the prior art is indicated by the following U.S. patents:

    ______________________________________                                        U.S. Pat. No.                                                                            Issue Date    Patentee                                             ______________________________________                                        3,414,292  December 3, 1968                                                                            S. Oldberg et al.                                    3,715,131  February 6, 1973                                                                            E. K. Hurley et al.                                  3,880,447  April 29, 1975                                                                              W. F. Thorn et al.                                   4,332,398  June 1, 1982  G. R. Smith                                          4,817,828  April 4, 1989 G. W. Goetz                                          4,832,300  June 27, 1989 J. F. Zionmek et al.                                 4,941,678  July 17, 1990 D. R. Lauritzen et al.                               ______________________________________                                    

The Oldberg et al. patent discloses a safety device for providingprotection for vehicle passengers comprising a folded inflatable crashbag closely surrounding an elongated cylindrical diffuser member, beingsecured thereto by clamps. The diffuser member defines a chamber inwhich an inflator comprising a fluid reservoir in an inner container isconcentrically located. For providing a tight seal the inner containeris seam welded at the opposite ends thereof to the diffuser member. Whenactivated by explosive means, fluid from the reservoir flows rearwardlyfrom one side only of the inflator against an adjacent inner wall of thediffuser member. The flow divides and is discharged forwardly through asingle row of longitudinally spaced apart openings, that are provided onone side only of the diffuser member, against a fixed baffle member. Thebaffle member divides and redirects the fluid rearwardly into theinflatable bag.

In the fabrication and assembly of inflatable devices for protectingvehicle passengers, the inflator poses the greatest potential hazard.Accidental initiation thereof during shipping, storing and installationin the safety device could result in injury to personnel and also causeproperty damage, particularly when the inflator is not of the thrustneutral type. Thus, in order to minimize the possibility of such injuryand damage, it is desirable to reduce the amount of handling to whichthe inflator is subjected during the fabrication and assembly of thesafety device. Installation of the inflator as a last operation in theassembly of the device would provide a substantial reduction in the riskof injury and damage. With the use of an inflator of the thrust neutraltype, the risk of such injury and damage would be further reduced.

The construction of the Oldberg et al. safety device is such as topreclude installation of the inflator as a last operation of theassembly of the device. Specifically, the inflatable bag is provided inclosely surrounding relation to the diffuser member, with the inflator,that is, the inner container, welded at the ends thereof to the diffusermember. Moreover, with fluid flowing from the reservoir of fluid fromone side only of the inflator and from one side only of the diffusermember, neither the inflator alone, nor the inflator and diffusermember, as a unit, are thrust neutral.

The Hurley et al. patent discloses a folded inflatable bag surrounding agas generator having a head assembly of cylindrical shape provided witha closed end and an open aft end that is closed by a closure plate. Acentrally positioned orifice that is normally closed by a rupture discis provided in the closure plate. Enclosing the cylindrical portion ofthe head assembly is a concentrically positioned diffuser having aclosed end in the shape of a dished head, thereby providing an annularcavity about the gas generator. Upon initiation of the gas generator,the rupture disc releases, in response to pressure in the head assemblyexceeding the burst pressure of the disc, thereby allowing the generatedgas to flow out of the orifice in the closure plate of the aft end ofthe gas generator and to impinge on the inner wall at the end of thediffuser. This causes the gas to be dispersed into the annular cavityand out of a plurality of openings spaced around the wall of thediffuser. With the generated gas flowing out of the aft end of the gasgenerator, the operation thereof is not thrust neutral. Nor does theHurley construction allow fabrication of the device with theinstallation of the gas generator as a last operation of the assembly.

The Thorn et al. patent discloses a folded inflatable bag positioned inclose contact with an elongated cylindrical gas generator. The gasgenerator is provided with rows of gas outlet ports that extend 360°around-the cylinder. The gas is discharged in opposing directions andproduces counteracting thrusts, and thus, is thrust neutral. A gasredirecting plate in the shape of a half cylindrical container ispositioned in spaced relation around the forwardly facing portion of thegas generator. The plate redirects forwardly discharged inflating gas ina rearward direction into the inflatable bag. Redirected gas togetherwith gas that directly is discharged into the inflatable bag deploy thebag, which normally is folded, to an inflated condition. In the storedposition thereof, the bag is positioned closely adjacent to and incontact with the rearward half side of the gas generator. This precludesinstallation of the gas generator as a last operation in the assembly ofthe apparatus.

The Smith patent discloses an inflatable restraint system including afolded inflatable cushion, a concentric elongated cylinderinflator-diffuser combination, and an elongated horizontally orientatednozzle. The inflator and diffuser are located within the confines of thefolded cushion and are connected as a unit to the side walls of ahousing therefor by means of bolts which extend into tapped bosses,which bosses are rigid with the combined unit. Consequently, neither thecombined unit, nor the inflator can be installed as a last operation inthe assembly of the system.

In the Goetz patent an elongated cylindrical inflator and a folded airbag are mounted in a rigid reaction canister which is fixed to thedashboard of a vehicle, with the orientation and arrangement of gasdischarge openings or exhaust ports in the inflator being such that,when activated, an initial flow of generated gas is directed rearwardlyby the inflator to inflate the bag. Excess gas flows from the inflatorin a forward direction into the surrounding environment. This result isachieved by using rupturable foil layers to close both forwardly andrearwardly directed inflator exhaust ports, with rupturing of therearwardly directed ports occurring at a pre-selected pressure that islower than that at which the forwardly directed ports rupture. Thus, theinflator is not thrust neutral, nor is it capable of installation as alast operation of the assembly of the apparatus because of thepositioning in the reaction canister of the folded air bag in closeproximity to the inflator.

As disclosed in the Goetz patent and the other aforementioned prior artpatents, it is known in prior art installations to provide a containerto house the air bag and the inflator. The container is generallyreferred to as a reaction canister and provides a medium for installingand retaining a module in the instrument panel by the utilization ofsuitable brackets.

The reaction canister provides protection for the inflator, thediffuser, if provided, and the air bag until the time of deployment ofthe bag. Additionally, the reaction canister absorbs the loads that areproduced upon deployment of the bag, which loads, typically, are large.Unless sufficiently absorbed, they can cause serious damage to theinterior of the vehicle, and in particular, to the instrument panel.

A drawback to the use of a reaction canister in an air bag module forpassenger protection is the envelope in the dashboard or instrumentpanel that is allotted for the installation of the module. Resultingrestrictions, usually in height, causes lengthened, that is, deeper, topand bottom panels in order to accommodate the folded volume of the-airbag. The bag is then restricted for unfolding and must travel rearwardlya distance greater than desirable before unfolding. Because of the largeamount of gas that is produced and the distance the bag needs to travelbefore unfolding, pressure builds up in the reaction canister to a levelthat tends to expand the canister and cause it to bulge. This condition,known as bell mouthing, is very destructive of the instrument panel, andis particularly objectionable in low speed crashes where other damage tothe vehicle is small.

The Zionmek et al. patent and the Lauritzen et al. patent disclose theuse of a tether strap to resist the spreading forces on the reactioncanister and thereby preclude bell mouthing upon deployment of the airbag. This technique allows the use of lighter weight and less expensivereaction canisters. The structural arrangement, however, leavessomething to be desired in respect of the introduction of undesirablecomplication into the manufacturing and assembling operations, andmoreover, does not allow installation of the inflator as a lastoperation in the assembly of the module.

Thus, there is a need and a demand for an improved reaction canister foruse in an air bag module for the passenger side of a vehicle.

SUMMARY OF THE INVENTION

An object of the invention is to provide a reaction canister including adiffuser integral therewith for housing and positioning an inflator andan inflatable bag and for directing a gas jet produced by the inflatorfor inflating the bag.

Another object of the invention is to provide a reaction canisterwherein the diffuser is a continuous circumference one piece diffuser.

Still another object of the invention is to provide such a reactioncanister wherein the diffuser is of the clamshell type having two halvesthat are generally equal in configuration with mating flanges extendingfrom each side of the halves.

A further object of the invention is to provide such a reaction canisterwherein the diffuser is of a modified clamshell type wherein the flangesare moved forward and connect to the top and bottom chute panels.

Another object of the invention is to provide such a reaction canisterwhich is so arranged as to permit installation of the inflator from theoutside of the reaction canister thereby allowing installation of theinflator as a last operation of assembly.

Still another object of the invention is to provide such a reactioncanister in which a thrust neutral inflator for safety may be used whileretaining the advantage of being able to direct a gas jet that can bebiased for best bag deployment.

In accomplishing these and other objectives of the invention, there isprovided a reaction canister that features the assembly integrallytherewith of a diffuser tube of continuous circumference. This type ofdiffuser tube provides a strong attachment means for the diffuser,indexing of the diffuser, containment of the generated gases ofcombustion at a lower gas pressure and provides a method of directingthe gas for better bag deployment.

Other benefits derived from the use of a diffuser tube integral with thereaction canister are an easy method of sealing the gas generator orinflator against leakage into the passenger compartment, and a simplerinflator installation from the outside of the reaction canister therebymaking the inflator installation a last operation of assembly. A thrustneutral inflator for safety may also be used while still retaining theadvantage of being able to direct a gas jet that can be biased for bestbag deployment. Still another benefit of the diffuser tube is a reduced,unsupported top and bottom panels depth that can help reduce thetendency to bellmouthing of the reaction canister.

The diffuser tube is a circumferential stress member wherein themajority of the stress from gas pressure can be taken out as tensilestress.

The reaction canister provides a vehicle for the incorporation orattachment of brackets for installation into the instrument panel of anautomotive vehicle. The reaction canister also provides a securereliable attachment for the inflatable bag.

The inflator is securely installed in the reaction canister. Thisinstallation is a unique feature of the present invention. The inflatorutilized has an elongated cylindrical shape and incorporates a gas flowoutlet or exhaust port arrangement that renders the inflator thrustneutral.

In accordance with one aspect of the present invention, the exhaust portarrangement of the inflator that is employed differs in an important andsignificant respect from that disclosed in the Thorn et al. patent inthat the rows of gas outlet openings or exhaust ports do not extend 360°around the cylindrical inflator. Instead, several rows of exhaust portsparallel to the longitudinal axis of the inflator are provided on eachside of the latter, with each row on one side being spaced 180° from arow on the other side.

In order to enable the use of the generated gas jet to direct thedeployment of the inflatable bag while retaining the safety feature ofthrust neutral for the gas generator, a diffuser tube has beenincorporated as an integral part of the reaction canister. This diffusertube, in effect, becomes a low pressure vessel with holes or slots fordirecting the gas jet.

In a first embodiment of the invention, a continuous circumference onepiece diffuser tube is provided for containing the initial reactioncanister pressure and for directing gas flow through breakout of theinflatable bag. Problems solved by the continuous circumference diffusertube used according to the invention and benefits derived therefrominclude the following:

1. The provision of structure to the body of the reaction canister,reducing the reacted surface area of the canister and thereby reducingthe tendency to bell mouthing.

2. Containment of the gas flow impingement to these same surfaces,reducing the bell mouthing.

3. Providing a barrier between the inflator and the inflatable bag,thereby reducing the tendency to bag damage due to heat and eliminatingbag and inflator interference at inflator installation.

4. Allowing the safety of using a thrust neutral inflator while stillretaining the benefit of a directed flow for bag deployment withoutimpingement of hot gases directly into the bag from the inflator.

In a second embodiment of the invention, the diffuser is in the form ofa clamshell having two halves. Substantial retention of the benefits ofthe continuous circumference diffuser is achieved by keeping thefastening of the two halves as close to the radial shape as possible. Inthis respect, the continuous circumference and clamshell diffuser tubesare functionally the same. The clamshell diffuser, however, is moreversatile.

Two types of clamshell diffuser tubes are disclosed. The first is theclassic clamshell where the two halves are generally equal inconfiguration with mating flanges extending from each side of thehalves.

This arrangement works well with reaction canisters that have a longvertical dimension. With a long vertical dimension the reaction canistertypically will have a shallow depth. This is the ideal configuration forlow air bag breakout pressures and for reducing the tendency to reactioncanister bell mouthing.

The second type of clamshell diffuser tube is a modified clamshell wherethe flanges are moved forward and connect to the top and bottom chutepanels. This type of diffuser is particularly useful where the verticaldimension of the reaction canister is shorter. Generally a reactioncanister with a small vertical dimension will have deeper chute panels.The forward location of the diffuser flanges and the attachment thereofto the top and bottom chute panels shorten the depths of these panelsand reduce the tendency of the reaction canister to bell mouth. Themodified clamshell diffuser provides a next to the top and bottom panelair bag installation, which leaves the flange area clear, where ventholes behind the bag in reaction canister venting where initial reactioncanister pressure can be vented to reduce the pressure in the reactioncanister until breakout of the inflatable bag.

The clamshell two halves provide the same circumferential benefits asdescribed above for the continuous circumferential diffuser describedhereinbefore after the two halves are fastened together. This fasteningcan be accomplished using any of the commonly accepted fastening methodsnow in use depending upon the circumstances of the reaction canisterassembly, that is, welding, riveting, screws, bolts, etc.

The flanges provide a method of bag attachment by using the two halffasteners to secure the bag. The flanges and fasteners provide a chuteattachment where chutes of different metals or plastics may be used.These same flanges become a strong structural area at the source of theloading, the inflator, where reaction canister installation bracketingmay be attached.

By way of illustration and not limitation, it is noted that theclamshell feature is especially adapted for use in reaction canisterswhere the vertical height is four and one-half inches (41/2") or 11.43centimeters. Where the height is less, a modified clamshell is provided.In this modified clamshell, the flanges are angled or moved forward toreduce the height dimension. This configuration has been used inreaction canisters with a height of three inches (3") or 7.62 cm. Anadvantage of the forward flange location is that tying the flanges tothe top and bottom panels reduces the length of the panels and thusreduces the area to be acted upon and consequently the tendency for thereaction canister to bell mouth.

In another modification, the clamshell concept is utilized in anassembly called a soft pack where the inflator and the inflatable bagare assembled to the diffuser in a normal manner and the bag is foldedto the diffuser without a chute. The soft pack is intended for use wherethe reaction canister is built into the instrument panel by themanufacturer of the vehicle. The pack contains the inflator, bag anddiffuser with studs for mounting in the instrument panel.

Continuous circumference and clamshell diffusers may be made of aluminumand steel and in combination. Similar configurations can be produced inextruded aluminum. There are limitations in the use of extruded aluminumin that the shape must be continuous over the entire length of thesection. The chute top and bottom panels must be continuous with eitherthe diffuser half or the cap half to be practical. Also, any featuresnormal to the section surfaces must be second operation fabrication suchas drilling, milling or punching.

All of the above arrangements may be duplicated in extruded aluminum ormagnesium and in some instances cast in these same metals. Extrudingpresents some constraints in that one of the diffuser tube halves isrequired to be included in the top and bottom panels of the chute. Thecap half is the logical half for this inclusion, leaving the diffuserhalf, being the smaller, left for second fabrication operations and/ordifferent material applications.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages, and specific objects attained by its use,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

With this description of the invention, a detailed description followswith reference to the accompanying drawings which form part of thespecification, of which:

FIG. 1 is a perspective schematic illustration of the external profileof an integral reaction canister and diffuser tube for an air bag moduleaccording to one embodiment of the invention;

FIG. 2 is a sectional view taken along the lines 2--2 of FIG. 1 showingthe continuous circumference one piece diffuser tube with integrallyformed top and bottom panels of the reaction canister;

FIG. 3 is an exploded fragmentary view of the reaction canister of FIG.1 illustrating the installation from the outside thereof of the inflatorin the diffuser tube;

FIG. 4 is a schematic section view of the diffuser tube and inflatorillustrating biasing of the jet flow of generated gases issuing from thediffuser slots;

FIG. 5 is a fragmented detailed section view illustrating the manner ofattachment of the air bag to the reaction canister;

FIG. 6 is a sectional view similar to that of FIG. 2 illustrating amodification wherein the diffuser tube and the top and bottom panels ofthe reaction canister are formed in two pieces;

FIG. 7 is a sectional view similar to FIG. 6 illustrating differentconfigurations for the top and bottom panels of the reaction canisterfor facilitating the use thereof with differently characterized vehicleinstrument panels;

FIG. 8 is a sectional view illustrating a diffuser tube of the clamshelltype in a narrow mouth width and deep top and bottom panel reactioncanister;

FIG. 9 is an exploded perspective view illustrating a clamshell diffusertube in a wide mouth width and shallow top and bottom panel reactioncanister;

FIG. 10 is a fragmentary sectional view taken along the lines 10--10 ofFIG. 9 showing in detail the air bag attachment and fasteningarrangement that may be employed in the reaction canister of FIG. 9;

FIG. 11 is a sectional view illustrating the assembled clamshelldiffuser and reaction canister arrangement of FIG. 9;

FIG. 12 is a perspective illustration of the envelope configuration of adiffuser tube cap with wide mouth clamshell reaction canister whereinthe length of the reaction canister is greater than that of theinflator;

FIG. 13 is a top plan view of the diffuser tube and reaction canister ofFIG. 12;

FIG. 14 is a side view of the diffuser tube and reaction canister ofFIG. 12;

FIG. 15 is an end view of the diffuser tube and reaction canister ofFIG. 12;

FIG. 16 is a section taken on the lines 16--16 of FIG. 14 showing thereaction canister body and the diffuser half of the diffuser tube formedin one piece;

FIG. 17 is a view showing an inflator having a flange at both ends andadapted for use in the wide mouth clamshell reaction canister of FIGS.12-16;

FIG. 18 is a fragmented perspective view on a larger scale illustratingthe attachment of an air bag to the wide mouth clamshell reactioncanister of FIG. 12;

FIG. 19 is a section taken along the lines 19--19 of FIG. 12 showing theair bag retained to the wide mouth clamshell reaction canister by an airbag retainer;

FIG. 20 is an exploded view illustrating a soft pack assembly containingthe inflator, inflatable bag and clamshell diffuser tube, with studs formounting the reaction canister in the instrument panel of a vehicle;

FIG. 21 is a fragmented view illustrating the bag installation in thesoft pack of FIG. 20;

FIG. 22 is a schematic section of a fabricated modified clamshellreaction canister;

FIG. 23 is a schematic section of another modified clamshell arrangementthat is similar to that of FIG. 22; and

FIG. 24 is an exploded view illustrating an extruded section modifiedclamshell reaction canister wherein the configuration involving thediffuser and the top and bottom panels is formed in two pieces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 an air bag module 10 constructed according to one embodimentof the present invention is shown mounted in the instrument panel 12 ofan automotive vehicle. For convenience of illustration the vehicle isnot shown, the instrument panel 12 being indicated in phantom. Themodule 10 includes a reaction canister 14 which houses a folded air bag16. A cover 18 for the air bag 16 is provided to prevent extraneousmaterial from falling thereon and also into the reaction canister 14.The manner of attaching the cover forms no part of the present inventionand, therefore, will not further be described herein.

Integrally formed with the reaction canister 14 is an elongatedcontinuous circumference one piece diffuser tube 20. Axially spacedinflating gas exit ports or slots 22 are provided in the portion of thewall of the diffuser tube 20 that faces the air bag 16. Positionedwithin the diffuser tube 20 and rigidly held in a selected angularrelation thereto, as further described hereinafter, is an inflator 24.Brackets 26 and 28 which are attached to the exterior of the reactioncanister 14 are provided for facilitating the installation of the module10 in the instrument panel 12. A decorative cover (not shown) whichmatches the profile of the surface of the instrument panel may beprovided. When the module 10 is installed, such decorative cover formspart of the surface of the instrument panel.

The reaction canister 14 includes a top panel 30 and a bottom panel 32,each of which have a respective first edge 30a, 32a and a respectivesecond edge 30b, 32b. The top panel 30 and bottom panel 32 inconjunction with the diffuser tube 20, a first end plate 34, and asecond end plate 36 define a cavity 38. The air bag 16, folded in aconventional manner, is housed in cavity 38. In FIG. 1 the cover 18 hasbeen partially broken away to reveal the folded air bag therein.

FIG. 2 shows a sectional view of the continuous circumference one piecediffuser tube 20 with the integrally formed top panel 30 and bottompanel 32 of the reaction canister 14. In other words, as shown, thediffuser 20 and the top panel 30 and the bottom panel 32 are formed as acontinuous or unitary structure. By way of example and not limitation,it is noted that, in a preferred embodiment, this configuration can beproduced in extruded aluminum. The slots 22 in the diffuser half of thediffuser tube 20, that half which faces the air bag 16 and the top panel30 and the bottom panel 32, are located and sized so as to provide adesired distribution of gas into the air bag 16 of gas that is generatedby the inflator 24. The inflator 24 has an elongated cylindricalconfiguration, as shown in FIG. 3, and is retained in the diffuser tube20, in concentric relation therewith, between the end plates 34 and 36.

In order to allow the inflator 24 to be inserted in the diffuser tube 20as a last operation in the assembly of the module 10, a circular opening40 is provided in a first end 41 of the second end plate 36 and asmaller opening 42 with a key slot therein is provided in a first end 43of the first end plate 34. Also, as shown, a flange 44 is provided on afirst end of the inflator 24 and a threaded keyed stud 46 is provided onthe second end thereof. The size of the opening 40 in the second endplate 36 is such as to allow the inflator 24 to be inserted in a snugfit form the second thereof, that having the stud 46 thereon. Similarly,the size of the keyed opening 42 in the first end plate 34 is such as tosnugly receive the stud 46. The arrangement is such that the relativeangular positions of the inflator 24 and the diffuser tube 20 about thecommon longitudinal axes 48 thereof is determined by the keyed opening42 in the first end plate 34 and the keyed inflator stud 46. A nut 50 onthe stud 46 serves to hold the end plates 34 and 36 against first andsecond ends 20c and 20d, respectively, of the diffuser tube 20 with theinflator 24 captured therein.

The second end 51 of the end plate 36 and the second end 53 of the endplate 34, that is, the ends thereof adjacent the air bag cover 18, asseen in FIG. 1, are fixedly attached to the first and second edges,respectively, of the top panel 30 and the bottom panel 32 by drivescrews 52 and 54. Screws 52 and 54 are screwed into grooves 56 and 58that are provided at the respectively associated forwardly located edgesof the top panel 30 and bottom panel 32.

The internal structure of the inflator 24 forms no part of the presentinvention and may be any of a number of known constructions that areavailable commercially. By way of example and not limitation, theinternal structure may comprise that disclosed in U.S. Pat. No.4,890,860 granted to Fred E. Schneiter on Jan. 2, 1990 and assigned tothe assignee of the present invention.

As shown in FIG. 3, several longitudinal rows of axially spaced openingsor exhaust ports 60 are provided on one side of inflator 24 parallel tothe longitudinal axis 48 thereof and several substantially identicallongitudinal rows of axially spaced exhaust ports 62 are provided on theother side thereof. The keying of the opening 42 in the first end plate30 and of the inflator stud 46 is such as to cause the inflator rows ofexhaust ports 60 and 62 t be selectively displaced angularly withrespect to the diffuser slots 22 in the diffuser tube 20. This, asillustrated in FIG. 4, enables biasing of the jet flow of gases issuingfrom the slots 22. Selection of the degree of bias may readily beaccomplished by appropriately angularly portioning, as by stamping, forexample, of the keying slots int he first end plate 32 relatively to thekeyed stud 50 on the end of the inflator 24.

For retaining the air bag 16 within the reaction canister 14, there isprovided, as best seen in FIGS. 2 and 5, a pair of elongated key holeshaped slots or grooves 68 and 70 which are provided at the forward endof the cavity 38 in association, respectively, with the top panel 30 andthe bottom panel 32. At each of the upper and lower sides of thegenerated gas inlet opening (not shown) of the air bag 16, the fabric isformed and sewn into a loop, specifically a loop 64 at the upper sideand a loop 66 at the lower side, as shown in FIG. 2. Each of the loops64 and 66 is inserted in a respectively associated elongated groove 68and 70 that are formed at the forward ends of the upper and lower panels30 and 32, respectively. Squeezing of the loops 64 and 66, as indicatedin FIG. 5, is required to facilitate such insertion through a narrowentry way provided into each of the grooves 68 and 70. Retention of theloops 64 and 66 in the grooves 68 and 70, and thereby attachment of theair bag 16 tot he reaction canister 14 and diffuser tube 20, is effectedby the insertion of rods 72 and 74 through the loops 64 and 66,respectively, and thereby through the respectively associated grooves 68and 70. The rods 72 and 74 may be fastened securely in fully insertedposition in any suitable manner.

In FIG. 6 there is illustrated a modification of the continuouscircumference diffuser and reaction canister arrangement shown in FIG. 2wherein the diffuser tube and the top and bottom panels of the reactioncanister are formed in two pieces instead of one. Thus, as shown in FIG.6, one piece comprises the top panel 30 and the bottom panel 32 whichare formed as a continuous unitary or integral structure with a portiononly of the diffuser tube, specifically the "diffuser half," designed20a. The other half of the diffuser tube, designated 20b and referred toherein as the "cap half," comprises the second piece.

In accordance with this embodiment of the invention, the two pieces areconfigured to interlock and join by dovetails. Assembly of the twopieces is by placing the two pieces in side-to-side relation and bysliding them relatively to each other over the entire length thereof.The two pieces may be rigidly retained in assembled relationship by oneor more bolts 76 that extend form the cap half 20b into the diffuserhalf.

The two piece reaction canister and diffuser tube arrangement of FIG. 6,similar to the one piece configuration of FIG. 2, features a diffusertube of continuous circumference and involves the attendance advantagesof this type of diffuser, as described hereinbefore.

While not shown in FIG. 6, the structure of the attachment of the airbag 16 to the reaction canister and diffuser tube may be as illustratedand described in connection with FIGS. 2 and 5.

FIG. 7 is a section that is similar to that of FIG. 6 and illustratesdifferent configurations of the top panel 30 and the bottom panel 32 ofthe reaction canister 14 for enabling the use thereof with instrumentpanels having different profiles. Thus, different spacings may beprovided between the top panel 30 and the bottom panel 32, and differentdepths may also be provided, as illustrated by top panel 30c and bottompanel 32c.

FIG. 8 is a schematic sectional view illustrating a diffuser tube 78 ofthe clamshell type in a narrow mouth width and deep top and bottom panelreaction canister.

The clamshell diffuser 78 may be made of aluminum or steel. It includesa diffuser half 78a and a cap half 78b which include mating flanges thatextend from each side of the halves for the attachment of the two halvesto each other. While the diffuser half 78a and cap half 78b may begenerally equal in construction, the cap half 78b, in FIG. 8, is shownas being made of heavier gage material for increased strength.Associated with the diffuser tube 78 and attached thereto by means ofthe mating flanges are a top panel 80 and a bottom panel 82 of areaction canister and also instrument panel mounting brackets 79 and 81.The several components are securely and rigidly attached to each otherby fasteners comprising studs 83 and nuts 85, which studs 83 extendthrough the slot in flanges of diffuser half 78a and cap half 78b andalso through cooperatively positioned flanges that are provided on thetop and bottom reaction canister panels 80 and 82, respectively, andalso on the bracket 81. For adding strength to the configuration the caphalf 78b of the diffuser 78 may be made of heavier gage material, asshown in FIG. 8, than the diffuser half 78a.

An exploded perspective view of clamshell diffuser tube in a wide mouthwidth and shallow top and bottom panel reaction canister is illustratedin FIG. 9. The clamshell diffuser tube, designated 86, includes adiffuser half 88 having slots 89 therein, and a cap half 90. Flanges 88aand 88b on the opposite sides of diffuser half 88 are arranged to matewith flanges 90a and 90b that are provided on the opposite sides of thecap half 90, as best seen int he sectional view of FIG. 11.

The reaction canister, indicated at 92 includes a top panel 94, a bottompanel 96, a first end plate 98 and a second end plate 100. Thesecomponents, in a preferred embodiments, are fabricated in a one piececonfiguration, and may be formed from aluminum sheet 0.080 inches thick.The clamshell diffuser 86 may be made of the same material.

As best seen in FIG. 11, the top panel 94 of the reaction canister 92includes a flange 102. The bottom panel 96 includes a flange 104. Thearrangement is such that, when the reaction canister 92 and the diffuser86 are in assembled relation, the flange 102 of the top panel 94, theflange 88a of the diffuser half 88 and the flange 90a of the cap half 90are superposed on one another, as are, also, the flange 104 of thebottom panel 96, the flange 88b of the diffuser half 88 and the flange90b of the cap half 90. The reaction canister 92 and the diffuser tube86 are retained in assembled relation by a plurality of studs 106 that,as shown, extend through aligned, spaced apart holes in the superposedflanges, the studs 106 being retained in the holes by nuts 108 tightenedthereon.

As best seen in FIG. 9, a hole or opening 110 with a key slot therein isprovided in the first end plate 98 of the reaction canister 92, and asubstantially half circle portion 112 is cut out of the second end plate100. The radius of curvature of the cut out portion 112 is somewhatsmaller than that of the diffuser half 88a, but is such, with thediffuser tube 88 and the reaction canister 92 in assembled relation, asto allow an inflator 114 to be inserted into the diffuser 88 in snugrelation therewith.

The internal structure of the inflator 114 may be identical to that ofthe inflator 24 described hereinbefore, and similarly thereto, includesa keyed stud 116 at one end and a flange 118 at the other end. The stud116 is arranged to extend through the keyed opening 110 in the first endplate 98 with the flange 118 at the other end of the inflator 114engaging the outer surface of the second end plate 100 and the adjacentend of the diffuser cap half 90. To that end, the flanges 90a and 90b atthat end of the end cap 90 are notched to allow the cap half 90 toextend toward the inflator flange 118 by an amount substantially equalto the thickness of the second end plate 100. A nut 120 is applied tostud 116 and tightened to hold the inflator rigidly within the diffuser86 in concentric relation therewith.

The inflator 114 may be similar in internal structure to the inflator 24previously described and includes several longitudinal rows of exhaustports (not shown) on opposite sides. As in the invention embodimentillustrated by reference to FIG. 4, bias of the flow of generated gasout of the exhaust ports may be selected, as desired, by appropriateangular placement of the key slot in the first end plate 98 of thereaction canister 92.

The attachment and fastening of an air bag 122 to the reaction canister92 and the diffuser tube 86 are illustrated in FIGS. 10 and 11. Asshown, the fabric of the air bag 122 at the gas inlet opening is foldedaround each of the opposed flanges 88a and 88b of the diffuser half 88of the diffuser tube 86 and captured between the respectively associatedflanges 90a, 88a, 102 and 90b, 88b, 194. Studs 106 extend through holesin the fabric that are in alignment with the spaced apart holes providedin the several flanges. The application of and tightening of nuts 108 onthe studs 106 secures the air bag 122 to the reaction canister 92 withthe inlet opening (not shown) thereof positioned in operative relationwith the generated gas exit slots 89 in the diffuser half 88 of thediffuser tube 86.

FIG. 12 illustrates, in a perspective view, the envelope configurationof a diffuser tube cap with a wide mouth clamshell reaction canisterwherein the length of the reaction canister is greater than the lengthof the inflator. FIGS. 13, 14 and 15 show top plan, side and end views,respectively, of the reaction canister. FIG. 16 is a section taken onthe lines 16--16 of FIG. 14 showing the reaction canister and thediffuser half of the diffuser tube formed in one piece. FIG. 17 is aview of the inflator employed in this embodiment of the invention.

As shown in FIG. 16, the top panel 124 and the bottom panel 126 of theclamshell reaction canister, designated 128, are integrally formed withthe diffuser half 130 of a diffuser tube 132. A cap half 134 of thediffuser tube 132 is attached to the diffuser half 130 by a plurality ofspaced apart studs 136 that extend downwardly from the reaction canister128 through holes therein in flange-like portions 130a and 130b formedadjacent both sides of the diffuser half 130 and through holes inalignment therewith in opposed flanges 138 and 140 that are provided onthe cap half 134. Nuts 142 applied to the studs 136 retain the cap half134 firmly secured to the reaction canister 128 and the diffuser half130.

The diffuser tube 132, as disclosed in FIGS. 12-16, differs from thediffuser tubes previously described herein in respect of the provisionof spaced apart slots on both sides thereof, specifically three slots144 facing the top panel 124 and three similar slots 146 facing thebottom panel 126. All of the slots 144 and 146 are angularly displacedfrom the horizontal plane of the diffuser tube 132, as seen in FIG. 16,by an angle of about 30°.

In addition to the one piece configuration of the diffuser half, toppanel 124 and bottom panel 126, the reaction canister 128 includes afirst end plate 148 and a second end plate 150. The ends of the endplates 148 and 150 may be joined to the respectively associated ends ofthe top and bottom panels 126 and 128 in any suitable manner, as forexample, by welding.

As shown in FIG. 17, the inflator 152 employed in this embodiment of theinvention is elongated, although of length shorter than the length ofthe reaction canister 128. The internal structure of the inflator 152may be similar or identical to the inflator 24 previously describedherein, but externally differs therefrom in the provision of a mountingflange at both ends, specifically a flange 154 at the right end and aflange 156 at the left end.

For enabling the insertion of the inflator 152 into the diffuser tube132 from outside of the reaction canister 128, a circular cut out 158 isprovided in the second end plate 150. For facilitating the retention ofthe inflator 152 in the diffuser tube 132 spaced slots 160 and 162 arecut out in the diffuser half 130 of the diffuser tube 132, with thespacing of the slots corresponding to the distance between the inflatorflanges 154 and 156. Slot 160, as best seen in FIG. 13, is positionedadjacent the first end plate 148 and the slot 162 is positioned adjacentthe second end plate 150. The width of each of the slots 160 and 162correspond to the widths of the flanges 154 and 156 of the inflator 152.Installation of the inflator 152 in the diffuser tube 132 thus merelyinvolves inserting or dropping the inflator 152 therein, whereupon theinflator flanges 154 and 156 engage individually associated ones of thespaced inflator retention slots 160 and 162 in the diffuser half 130.

For predetermining the relative angular position of the inflator 152relatively tot he axially spaced inflating gas exit slots 144 and 146 inthe diffuser portion 130 of the diffuser tube 132, a niche 163 isprovided on the inflator retention slot 162, as shown in FIG. 13, and amating projection 165 is provided on a peripheral edge of the inflatorflange 154, as shown in FIG. 17.

As shown in FIGS. 12 and 13, a plurality of holes 164 may be provided inthe top of the diffuser half, providing exit passages from the diffusertube 132 in addition to the opposed sets of slots 144 and 146. Generatedgas flowing out of the slots 164 from the diffuser tube 132 flowdirectly into the associated air bag and serves to relieve the pressuresomewhat in the diffuser tube 132.

In effecting the attachment of an air bag 166 to the wide mouthclamshell reaction canister 128, as best seen in FIGS. 18 and 19, themouth of the air bag 166 is sewn into a rectangle with a doublethickness of material tab extending down along each side. These tabshave holes burnt into them that are folded under and over the studs 136in a bag retainer 168. With the air bag tabs over the studs 136 on bothsides of the bag retainer 168, the assembly is assembled in the chutewith the studs 136 passing through the holes in the chute. The inflator152 is then installed from the back side with the cap flanges 138 and140 and nuts 142 installed.

FIG. 20 is an exploded view illustrating the use of the clamshellfeature in a soft pack installation. The soft pack is intended for usewhere the reaction canister is built into the instrument panel by theautomobile manufacturer. As shown, the soft pack contains an inflator170, a folded air bag 172, a diffuser tube 174 having a cap half 176 anda diffuser half 178 with studs 180 for mounting in the instrument panel(not shown). A curved flange 177 is provided at one end of the diffuserhalf 178 of the diffuser tube 174 and a similar curved flange 179 isprovided at the other end thereof.

The internal structure of the inflator 170 may be identical to that ofthe inflator 24 previously described herein and includes a flange 182 atone end and a keyed stud 184 at the other end. A keyed circularretaining plate 186 and nut 188 provided for retaining the inflatorconcentrically within the diffuser tube 178 when inserted therein uponassembly of the soft pack. For predetermining the relative angularpositions of sets of exhaust ports 190 in the inflator 170 and exitslots 192 of the diffuser half 178, the keyed retaining plate 186 isprovided with a pin-like projection 194 on the circumference thereof andthe diffuser half 178 is provided with a cooperating mating slot 196 onthe adjacent edge thereof.

The fragmented view of FIG. 21 illustrates the installation of thefolded air bag 172 in the soft pack of FIG. 20 and shows an edge of thegenerated gas inlet opening (not shown) of the air bag 172 as crimpedbetween folded portions of the flanges 200 of the cap half 176 of thediffuser tube 174. This air bag retention technique allows for the useof fewer studs or other fasteners.

In the modified clamshell reaction canister 202 illustrated in FIG. 22,a lower or cap portion 204 of a diffuser tube 206 is enlarged, as shown,to provide more area for end porting hybrid inflator gas passage to thecenter of the reaction canister 202. The two halves of the diffuser tube206, that is, the cap portion 204 and a diffuser portion 208, may bespot welded together thereby to provide radial continuity for strength.The reaction canister 202, as shown, also is provided with a top panel210 and a bottom panel 212. Each of panels 210 and 212 is attached byscrews 214 to an individually associated one of opposed forwardlyextending flange portions 216 and 218 of the diffuser portion 208 of thediffuser tube 206. Forwardly extending flange portions 216 and 218 areintegrally formed with respectively associated rearwardly extendingflange portions 220 and 222, as shown.

For the attachment of an air bag 224 to the reaction canister 202, theair bag gas inlet or mouth is sewn into a rectangle with a doublethickness of material tab down each side and a forward extension that issewn into a pocket 226. These pockets 226 are slipped over the forwardlyextending flange extensions 216 and 218 of the diffuser portion 208. Thebag 226 and diffuser portion 208 is then installed into the chute andfastened with screws 214 through the air bag 226 and the diffuserflanges 216 and 218.

A modified clamshell reaction canister arrangement that is similar tothat shown in FIG. 22 is shown in FIG. 23. Again, the two halves, alower or cap portion 28 and a diffuser portion 230 of a diffuser tube232, are welded together for radial Continuity. The lower or cap portion228 is enlarged similarly to the cap portion 204 of FIG. 22 for hybridinstallation. In the arrangement of FIG. 23, however, the diffuserportion 230 of the diffuser tube 232 is made of a heavier gage materialto provide a strong member across top and bottom panels 234 and 236,respectively, thereby effectively to shorten their length, whereby areduction in the tendency to bell mouth is achieved.

The attachment of an air bag (not shown) may be made to the modifiedclamshell arrangement of FIG. 23 in the same manner as that employed inFIG. 22.

FIG. 24 is an exploded view illustrating an extruded section modifiedclamshell reaction canister 238 wherein the configuration of thediffuser 240 and the top and bottom panels 242 and 244, respectively, isformed in two pieces. Specifically, as shown, a cap portion 246 of thediffuser 240 and the top panel 242 and the bottom panel 244 are extrudedas a single piece, and a diffuser portion is fabricated as a separatepiece. Screws 250 and nuts 252 are provided for fastening the two piecestogether and retaining them in securely assembled relation and for theattachment of an air bag (not shown) between opposed flanges 254, 256 onthe cap portion 246 and opposed flanges 258 and 260 on the diffuserportion 248. For improving the retentive capability of such air bagattachment technique, the opposed flanges 254 and 256 on the cap portion246 may be provided with serrated surfaces 262 and 264, respectively, asshown, during the extrusion process.

Thus, in accordance with the invention, there has been provided animproved reaction canister assembly enabling:

(a) a simpler installation of the inflator from outside the reactioncanister thereby making possible the installation of the inflator as alast operation of assembly;

(b) the inflating gases generated by the inflator to be contained at alower pressure;

(c) an efficacious method of sealing the inflator against leakage intothe passenger compartment; and

(d) the use of a thrust neutral inflator for safety while stillretaining the advantage of being able to direct a gas flow that can bebiased for best bags deployment.

Briefly summarizing, these and other advantages, as described herein,have been achieved by the use of a reaction canister including adiffuser tube integral therewith for housing and positioning an inflatorand an inflatable bag and for directing an inflating gas jet produced bythe inflator for inflating the bag. In one embodiment, the diffuser is acontinuous circumference one piece diffuser. In another embodiment, thediffuser is a continuous circumference two piece diffuser. In stillother embodiments, the diffuser is of a clamshell type having two halvesthat generally are equal in configuration with mating flanges thatextend from each side of each half. A diffuser of a modified clamshelltype is also contemplated wherein the flanges are moved forward therebyeffectively reducing the depth of the top panel and the bottom panel ofthe reaction canister and concomitantly reducing the tendency to bellmouth.

We claim:
 1. For use in an inflatable restraint system reaction canisterbuilt in the instrument panel of an automobile by the automobilemanufacturer, a soft pack assembly comprising:a diffuser tube of theclamshell type having a diffuser portion and a cap portion each of whichhas opposed sides from which mating flanges extend, said diffuserportion having a plurality of spaced inflating gas exit slots formedtherein, an inflatable bag having an inflating gas inlet openingpositioned in folded relation against said diffuser portion of saiddiffuser tube with said inflating gas inlet opening positioned incommunicating relation with said inflating gas inlet slots formed insaid diffuser portion, with peripheral portions of said inflating gasinlet opening being positioned between said mating flanges for retentiontherebetween. an elongated inflator positioned in said diffuser tube insubstantially concentric relation therewith, means for retaining saidinflator securely in said diffuser tube, and means including studsextending through said mating flanges and said peripheral portions ofsaid inflatable bag for securing said mating flanges of said diffuserportion and said cap portion with said peripheral portion of saidinflatable bag crimped therebetween, and for mounting said diffuser tubeand inflatable bag in assembled relation in the reaction canister builtin the instrument panel of an automobile by the automobile manufacturer.2. For use in an inflatable restraint system reaction canister built inthe instrument panel of an automobile by the automobile manufacturer, asoft pack assembly, as defined by claim 1,wherein each of the matingflanges of said cap portion of said diffuser is folded and saidperipheral portions of said inflating gas inlet opening are crimpedbetween folded portions of said mating flanges of said cap portion. 3.For use in an inflatable restraint system for motor vehicles, aclamshell reaction canister comprising:a reaction canister having a toppanel and a bottom panel, a diffuser tube of the clamshell type having adiffuser portion and a cap portion, each of which diffuser tube portionshas opposed sides form each of which sides a mating flange extends,first means connecting the mating flanges on adjacent ones of the sidesof each of said diffuser tube portions to said top panel of saidreaction canister, and second means connecting the mating flanges on theother adjacent ones of the sides of each of said diffuser tube portionsto said bottom panel of said reaction canister.
 4. For use in aninflatable restraint system for motor vehicles, as defined in claim3,wherein said mating flanges of said diffuser tube are placed in such aposition on the opposed sides thereof that the diffuser tube is of theclamshell type having two halves that are generally equal inconfiguration.
 5. For use in an inflatable restraint system for motorvehicles, as defined in claim 3,wherein said mating flanges of saiddiffuser tube are moved forward whereby the forward location of saiddiffuser tube flanges and the attachment thereof to said top and bottompanels of said reaction canister shorten the depth of said top andbottom panels and reduce the tendency of said reaction canister to bellmouth.
 6. For use in an inflatable restraint system reaction canisterbuilt in the instrument panel of an automobile by the automobilemanufacturer, a soft pack assembly, as defined by claim 1,wherein saiddiffuser portion of said diffuser tube has two ends, wherein saidelongated inflator includes sets of exhaust ports along the lengththereof and includes a flange at one end and a keyed stud at the otherend, and wherein said means for retaining said inflator securely in saiddiffuser tube includes a curved flange provided at one end of saiddiffuser portion of said diffuser tube, against which curved flange saidflange of said inflator mates when said inflator is inserted in saiddiffuser tube upon assembly of the soft pack, a similar curved flangeprovided at the other end of said diffuser portion of said diffusertube, said similar curved flange having a slot on the edge thereof, akeyed substantially similar retaining plate and a nut cooperating withsaid stud of said inflator for retaining said inflator substantiallyconcentrically within said diffuser tube when inserted therein, saidkeyed retaining plate having a keyed hole into which said keyed stud ofsaid inflator fits in cooperating relation and having a pin-likeprojection on the circumference thereof, said pin-like projection matingwith said slot on said similar curved flange of said diffuser portionfor predetermining the relative angular positions of said sets ofexhaust ports of said inflator and said gas slots of said diffuserportion of said diffuser tube.